Caseinolytic and glyoprotein hydrolase activity of Streptococcus mutans.

Proteolytic hydrolysis of casein and porcine or bovine glycoproteins by S mutans was demonstrated in the present study. Caseinolytic activity was found in both the soluble contents of the cells and the cellular debris after rupture of the cells. However, caseinolytic activity could not be demonstrated after growth in the culture fluid from any of the strains of S mutans tested. The soluble fractions of S mutans did not possess glycoprotein hydrolase activity toward porcine or bovine glycoprotein, but glycoprotein hydrolase activity was present in both the cell-debris preparation from cells and in the culture fluid after growth of the cultures. Based on these observations, S mutans may possess several different types of proteinase enzymes with differing specificities for protein substrates.